HP48G Clock Variability

[Jonathan Busby]

(02-11-2021 09:32 PM)KeithB Wrote:  The whole point of the PLL is that, because of the feedback, the VCO does not need to be accurate, The crystal accuracy should be setting the frequency accuracy

My point exactly : If the clock is variable, and from my experience the crystal oscillator is usually *not* variable, then something "weird" is going on with the PLL, perhaps with the VCO, phase detector or low-pass filter.

Regards,

Jonathan